Weather Blog

WEATHER BLOG

August 21, 2008|By FRANK ROYLANCE

Stuart Godwin Jr. wrote from Chestertown a while back to ask: "What is the relationship between Dew Point and Relative Humidity? Is one dependent on the other?" You bet. Warmer air can hold more water vapor. The RH is a percentage, telling us how close to saturation (100 percent) the air is at ground level. As air cools, it can hold less moisture, and RH rises. At the dew-point temperature, it's saturated (100 percent), and the vapor condenses as rain or fog.